Results for "Stefan Luettgen"

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Analyzing Business Process Anomalies Using AutoencodersMar 03 2018Businesses are naturally interested in detecting anomalies in their internal processes, because these can be indicators for fraud and inefficiencies. Within the domain of business intelligence, classic anomaly detection is not very frequently researched. ... More
BINet: Multi-perspective Business Process Anomaly ClassificationFeb 08 2019In this paper, we introduce BINet, a neural network architecture for real-time multi-perspective anomaly detection in business process event logs. BINet is designed to handle both the control flow and the data perspective of a business process. Additionally, ... More
The midpoint between dipole and parton showersJun 16 2015Sep 19 2015We present a new parton-shower algorithm. Borrowing from the basic ideas of dipole cascades, the evolution variable is judiciously chosen as the transverse momentum in the soft limit. This leads to a very simple analytic structure of the evolution. A ... More
A shortcut to (sun)flowers: Kernels in logarithmic space or linear timeApr 30 2015We investigate whether kernelization results can be obtained if we restrict kernelization algorithms to run in logarithmic space. This restriction for kernelization is motivated by the question of what results are attainable for preprocessing via simple ... More
The H-Covariant Strong Picard GroupoidSep 08 2004Apr 25 2005The notion of H-covariant strong Morita equivalence is introduced for *-algebras over C = R(i) with an ordered ring R which are equipped with a *-action of a Hopf *-algebra H. This defines a corresponding H-covariant strong Picard groupoid which encodes ... More
Reliability of regulatory networks and its evolutionMay 27 2008The problem of reliability of the dynamics in biological regulatory networks is studied in the framework of a generalized Boolean network model with continuous timing and noise. Using well-known artificial genetic networks such as the repressilator, we ... More
Reliability of genetic networks is evolvableJul 10 2007Control of the living cell functions with remarkable reliability despite the stochastic nature of the underlying molecular networks -- a property presumably optimized by biological evolution. We here ask to what extent the property of a stochastic dynamical ... More
Finite-Size Corrections for Ground States of Edwards-Anderson Spin GlassesOct 28 2011May 30 2012Extensive computations of ground state energies of the Edwards-Anderson spin glass on bond-diluted, hypercubic lattices are conducted in dimensions d=3,..,7. Results are presented for bond-densities exactly at the percolation threshold, p=p_c, and deep ... More
Superstability of the yeast cell cycle dynamics: Ensuring causality in the presence of biochemical stochasticityMay 05 2006Gene regulatory dynamics is governed by molecular processes and therefore exhibits an inherent stochasticity. However, for the survival of an organism it is a strict necessity that this intrinsic noise does not prevent robust functioning of the system. ... More
Weak Limit of the 3-State Quantum Walk on the LineApr 04 2014May 21 2014We revisit the one dimensional discrete time quantum walk with 3 states and the Grover coin. We derive analytic expressions for observed the localization, an long time approximation for the probability density function (PDF). We also connect the time ... More
Streaming KernelizationMay 06 2014Kernelization is a formalization of preprocessing for combinatorially hard problems. We modify the standard definition for kernelization, which allows any polynomial-time algorithm for the preprocessing, by requiring instead that the preprocessing runs ... More
On the commutability of homogenization and linearization in finite elasticityNov 16 2010May 16 2011We study non-convex elastic energy functionals associated to (spatially) periodic, frame indifferent energy densities with a single non-degenerate energy well at SO(n). Under the assumption that the energy density admits a quadratic Taylor expansion at ... More
Geometry on totally separably closed schemesMar 10 2015We prove, for quasicompact separated schemes over ground fields, that Cech cohomology coincides with sheaf cohomology with respect to the Nisnevich topology. This is a partial generalization of Artin's result that for noetherian schemes such an equality ... More
Slim Sets of Binary TreesJun 28 2010A classical problem in phylogenetic tree analysis is to decide whether there is a phylogenetic tree $T$ that contains all information of a given collection $\cP$ of phylogenetic trees. If the answer is "yes" we say that $\cP$ is compatible and $T$ displays ... More
Annealing schedule from population dynamicsMar 04 1999We introduce a dynamical annealing schedule for population-based optimization algorithms with mutation. On the basis of a statistical mechanics formulation of the population dynamics, the mutation rate adapts to a value maximizing expected rewards at ... More
Covariant Strong Morita Theory of Star Product AlgebrasJan 27 2009In this note we recall some recent progress in understanding the representation theory of *-algebras over rings C = R(i) where R is ordered and i^2 = -1. The representation spaces are modules over auxiliary *-algebras with inner products taking values ... More
Omega_bbb excited-state spectroscopy from lattice QCDFeb 11 2013Triply heavy baryons are very interesting systems analogous to heavy quarkonia, but are difficult to access experimentally. Lattice QCD can provide precise predictions for these systems, which can be compared to other theoretical approaches. In this work, ... More
Bottomonium spectrum at order v^6 from domain-wall lattice QCD: precise results for hyperfine splittingsJul 22 2010Oct 27 2010The bottomonium spectrum is computed in dynamical 2+1 flavor lattice QCD, using NRQCD for the b quarks. The main calculations in this work are based on gauge field ensembles generated by the RBC and UKQCD collaborations with the Iwasaki action for the ... More
Prediction of the Omega_bbb mass from lattice QCDAug 18 2010Oct 27 2010The mass of the triply heavy baryon Omega_bbb is calculated in lattice QCD with 2+1 flavors of light sea quarks. The b quark is implemented with improved lattice NRQCD. Gauge field ensembles from both the RBC/UKQCD and MILC collaborations with lattice ... More
Relativistic, QED and nuclear effects in highly charged ions revealed by resonant electron-ion recombination in storage ringsMay 28 2008Aug 15 2008Dielectronic recombination (DR) of few-electron ions has evolved into a sensitive spectroscopic tool for highly charged ions. This is due to technological advances in electron-beam preparation and ion-beam cooling techniques at heavy-ion storage rings. ... More
Photorecombination and Photoionization Experiments at Heavy-Ion Storage-Rings and Synchrotron-Light SourcesAug 29 2003Recent experimental work on the photorecombination and the photoionization of astrophysically relevant atomic ions employing the merged-beams technique at heavy-ion storage-rings and synchrotron-light sources, respectively, is summarized. The resulting ... More
JyNI - Using native CPython-Extensions in JythonApr 25 2014Apr 29 2014Jython is a Java based Python implementation and the most seamless way to integrate Python and Java. However, it does not support native extensions written for CPython like NumPy or SciPy. Since most scientific Python code fundamentally depends on exactly ... More
The Efficiency of Density DeconvolutionJul 03 2015The density deconvolution problem involves recovering a target density g from a sample that has been corrupted by noise. From the perspective of Le Cam's local asymptotic normality theory, we show that non-parametric density deconvolution with Gaussian ... More
Probabilistic Constraint Logic ProgrammingNov 11 1997This paper addresses two central problems for probabilistic processing models: parameter estimation from incomplete data and efficient retrieval of most probable analyses. These questions have been answered satisfactorily only for probabilistic regular ... More
Computational Aspects of the Hausdorff Distance in Unbounded DimensionJan 07 2014We study the computational complexity of determining the Hausdorff distance of two polytopes given in halfspace- or vertex-presentation in arbitrary dimension. Subsequently, a matching problem is investigated where a convex body is allowed to be homothetically ... More
Commensurability of knots and L^2-invariantsApr 11 2012Apr 26 2012We show that the L^2-torsion and the von Neumann rho-invariant give rise to commensurability invariants of knots.
Signal-Flow Based Runge-Kutta Methods for the Simulation of Complex NetworksApr 24 2015Complex dynamical networks appear in a wide range of physical, biological, and engineering systems. The coupling of subsystems with varying time scales often results in multirate behavior. During the simulation of highly integrated circuits, for example, ... More
An uncertainty principle on compact manifoldsNov 05 2014Breitenberger's uncertainty principle on the torus $\mathbb{T}$ and its higher-dimensional analogue on $\mathbb{S}^{d-1}$ are well understood. We give describe an entire family of uncertainty principles on compact manifolds $(M,g)$, which includes the ... More
Dispersion dynamics for the defocusing generalized Korteweg-de Vries equationMay 02 2013Jun 05 2013We study dispersion for the defocusing gKdV equation. It is expected that it is not possible for the bulk of the $L^2-$mass to concentrate in a small interval for a long time. We study a variance-type functional exploiting Tao's monotonicity formula in ... More
Directional Poincare inequalities along mixing flowsApr 22 2015Mar 11 2016We provide a refinement of the Poincar\'{e} inequality on the torus $\mathbb{T}^d$: there exists a Lebesgue-null set $\mathcal{B} \subset \mathbb{T}^d$ of directions such that for every $\alpha \in \mathcal{B}$ there is a $c_{\alpha} > 0$ with $$ \|\nabla ... More
On Eigenvectors of Random Band Matrices with Large BandJul 22 2013Oct 21 2014We study random, symmetric $N \times N$ band matrices with a band of size $W$ and Bernoulli random variables as entries. This interpolates between nearest neighbour interaction $W = 1$ and Wigner matrices $W = N$. Eigenvectors are known to be localized ... More
A Dynamical Thermostat Approach To Financial Asset Price DynamicsNov 16 2000A dynamical price formation model for financial assets is presented. It aims to capture the essence of speculative trading where mispricings of assets are used to make profits. It is shown that together with the incorporation of the concept of risk aversion ... More
Blind Turing-Machines: Arbitrary Private Computations from Group Homomorphic EncryptionDec 11 2013Secure function evaluation (SFE) is the process of computing a function (or running an algorithm) on some data, while keeping the input, output and intermediate results hidden from the environment in which the function is evaluated. This can be done using ... More
Few-body hierarchy in non-relativistic functional renormalization group equations and a decoupling theoremJan 28 2013Aug 27 2014For non-relativistic quantum field theory in the few-body limit with instantaneous interactions it is shown within the functional renormalization group formalism that propagators are not renormalized and that the renormalization group equations of one-particle ... More
Simulations of Ground State Fluctuations in Mean-Field Ising Spin GlassesJun 06 2009Mar 28 2010The scaling of fluctuations in the distribution of ground-state energies or costs with the system size N for Ising spin glasses is considered using an extensive set of simulations with the Extremal Optimization heuristic across a range of different models ... More
Reduction of Spin Glasses applied to the Migdal-Kadanoff Hierarchical LatticeFeb 20 2003Mar 26 2003A reduction procedure to obtain ground states of spin glasses on sparse graphs is developed and tested on the hierarchical lattice associated with the Migdal-Kadanoff approximation for low-dimensional lattices. While more generally applicable, these rules ... More
Aging Random WalksFeb 15 1997Aging refers to the property of two-time correlation functions to decay very slowly on (at least) two time scales. This phenomenon has gained recent attention due to experimental observations of the history dependent relaxation behavior in amorphous materials ... More
Spin Glass Stiffness in zero DimensionsApr 11 2006A unique analytical result for the Migdal-Kadanoff hierarchical lattice is obtained. The scaling of the defect energy for a zero-dimensional spin glass is derived for a bond distribution that is continuous at the origin. The value of the ``stiffness'' ... More
Coherent states, line bundles and divisorsJul 14 1998For homogeneous simply connected Hodge manifolds it is proved that the set of coherent vectors orthogonal to a given one is the divisor responsible for the homogeneous holomorphic line bundle of the coherent vectors. In particular, for naturally reductive ... More
Meissel's theorem in additive arithmetical semigroupsSep 25 2005We show how to control the error term in Mertens' formula and related theorems in the context of additive arithmetical semigroups and carry over an old related result of Meissel.
Persistent Hall Voltage and Current in the Fractional Quantum Hall RegimeApr 02 1997The persistent Hall voltage and current in an isolated annulus in a strong perpendicular magnetic field, at odd inverse filling factor, and in the presence of a weak constriction is obtained as a function of temperature, and flux piercing the annulus. ... More
Tutorial on loop integrals which need regularisation but yield finite resultsFeb 18 2014In this pedagogical note I will discuss one-loop integrals, where (i) different regions of the integration region lead to divergences and (ii) where these divergences cancel in the sum over all regions. These integrals cannot be calculated without regularisation, ... More
Feynman integrals and multiple polylogarithmsMay 07 2007May 10 2007In this talk I review the connections between Feynman integrals and multiple polylogarithms. After an introductory section on loop integrals I discuss the Mellin-Barnes transformation and shuffle algebras. In a subsequent section multiple polylogarithms ... More
The Art of Computing Loop IntegralsApr 07 2006A perturbative approach to quantum field theory involves the computation of loop integrals, as soon as one goes beyond the leading term in the perturbative expansion. First I review standard techniques for the computation of loop integrals. In a second ... More
Expansion around half-integer values, binomial sums and inverse binomial sumsFeb 12 2004I consider the expansion of transcendental functions in a small parameter around rational numbers. This includes in particular the expansion around half-integer values. I present algorithms which are suitable for an implementation within a symbolic computer ... More
Cancellation of infrared divergences at NNLOOct 14 2003Perturbative calculations at next-to-next-to-leading order for multi-particle final states require a method to cancel infrared singularities. I discuss how to setup the subtraction method at NNLO.
Jet algorithms in electron-positron annihilation: Perturbative higher order predictionsNov 29 2010Jun 30 2011This article gives results on several jet algorithms in electron-positron annihilation: Considered are the exclusive sequential recombination algorithms Durham, Geneva, Jade-E0 and Cambridge, which are typically used in electron-positron annihilation. ... More
NNLO corrections to 3-jet observables in electron-positron annihilationJul 21 2008Oct 14 2008I report on a numerical program, which can be used to calculate any infrared safe three-jet observable in electron-positron annihilation to next-to-next-to-leading order in the strong coupling constant alpha_s. The results are compared to a recent calculation ... More
Status of jet cross sections to NNLOJun 29 2006I review the state-of-the-art for fully differential numerical NNLO programs. Topics which are covered include the calculation of two-loop amplitudes, multiple polylogarithms, cancellation of infra-red divergences at NNLO and the efficient generation ... More
QCD corrections to e+ e- --> 4 jetsNov 30 1999We report on the next-to-leading order QCD calculation for e+ e- --> 4 jets. We explain some modern techniques which have been used to calculate the one-loop amplitudes efficiently. We further report on the general purpose numerical program ``Mercutio'', ... More
Massive gauge bosons from the conservation of topological winding numbersSep 28 1999We consider a U(1) x SU(2) gauge theory on the four-dimensional manifold S^1 x S^3. If we make the assumption that only gauge transformations connected to the identity are allowed, the winding numbers of U(1) around S^1 and of SU(2) around S^3 become ... More
Equation of State in a Generalized Relativistic Density Functional ApproachApr 07 2015The basic concepts of a generalized relativistic density functional approach to the equation of state of dense matter are presented. The model is an extension of relativistic mean-field models with density-dependent couplings. It includes explicit cluster ... More
The Longstaff--Schwartz algorithm for Lévy models: Results on fast and slow convergenceFeb 13 2008Apr 06 2011We investigate the Longstaff--Schwartz algorithm for American option pricing assuming that both the number of regressors and the number of Monte Carlo paths tend to infinity. Our main results concern extensions, respectively, applications of results by ... More
Co-nondeterminism in compositions: A kernelization lower bound for a Ramsey-type problemJul 19 2011Dec 13 2011Until recently, techniques for obtaining lower bounds for kernelization were one of the most sought after tools in the field of parameterized complexity. Now, after a strong influx of techniques, we are in the fortunate situation of having tools available ... More
Coupling the Superstring to a D-Brane Ramond-Ramond BackgroundAug 13 2001Dec 03 2001We propose a new approach for coupling the type II superstring to the Ramond-Ramond background of D-branes in the RNS formalism, alternative to introducing RR vertex operators. It is based on the mixing between Ramond-Ramond p-form excitations in the ... More
Subalgebras of bigraded Koszul algebrasNov 29 2000Nov 30 2000We show that diagonal subalgebras and generalized Veronese subrings of a bigraded Koszul algebra are Koszul. We give upper bounds for the regularity of sidediagonal and relative Veronese modules and apply the results to symmetric algebras and Rees rings. ... More
Optical tsunamis: shoaling of shallow water rogue waves in nonlinear fibers with normal dispersionJan 24 2013Apr 26 2013In analogy with ocean waves running up towards the beach, shoaling of prechirped optical pulses may occur in the normal group-velocity dispersion regime of optical fibers. We present exact Riemann wave solutions of the optical shallow water equations ... More
An elementary model of price dynamics in a financial market: Distribution, Multiscaling & EntropyFeb 14 2006Stylized facts of empirical assets log-returns $Z$ include the existence of (semi) heavy tailed distributions $f_Z(z)$ and a non-linear spectrum of Hurst exponents $\tau(\beta)$. Empirical data considered are daily prices of 10 large indices from 01/01/1990 ... More
Diffractive Dijet Production with a Leading Proton in ep Collisions at HERAAug 19 2015The production of dijets with a tagged forward proton is measured at HERA. The data were recorded with the H1 detector at DESY in the years 2006-2007. Events with a leading proton are detected using the very forward proton spectrometer of the H1 detector. ... More
Enrichment as Categorical Delooping I: Enrichment Over Iterated Monoidal CategoriesApr 02 2003Oct 23 2003The 2-category V-Cat of categories enriched over a braided monoidal category V is not itself braided in any way that is based upon the braiding of V. The exception is the case in which V is symmetric, which leads to V-Cat being symmetric as well. This ... More
Dimension reduction for functionals on solenoidal vector fieldsApr 21 2010We study integral functionals constrained to divergence-free vector fields in $L^p$ on a thin domain, under standard $p$-growth and coercivity assumptions, $1<p<\infty$. We prove that as the thickness of the domain goes to zero, the Gamma-limit with respect ... More
Existence and symmetry of minimizers for nonconvex radially symmetric variational problemsApr 30 2007Nonconvex functionals with spherical symmetry are studied. Existence of one and radial symmetry of all global minimizers is shown with an approach based on convex relaxation.
On the sign of regular algebraic polarizable automorphic representationsJun 05 2013Jul 08 2014We remove a parity condition from the construction of automorphic Galois representations carried out in the Paris Book Project. We subsequently generalize this construction to the case of `mixed-parity' (but still regular essentially self-dual) automorphic ... More
An estimate of free entropy and applicationsFeb 07 2004We obtain an estimate of free entropy of generators in a type ${II}_1$-factor $\mc{M}$ which has a subfactor $\mc{N}$ of finite index with a subalgebra $\mc{P}=\mc{P}_1\vee\mc{P}_2\subset\mc{N}$ where $\mc{P}_1=\mc{R}_1'\cap\mc{P}$, $\mc{P}_2=\mc{R}_2'\cap\mc{P}$ ... More
The operator product expansion for perturbative quantum field theory in curved spacetimeMay 11 2006We present an algorithm for constructing the Wilson operator product expansion (OPE) for perturbative interacting quantum field theory in general Lorentzian curved spacetimes, to arbitrary orders in perturbation theory. The remainder in this expansion ... More
A General PCT Theorem for the Operator Product Expansion in Curved SpacetimeDec 06 2002We consider the operator product expansion for quantum field theories on general analytic 4-dimensional curved spacetimes within an axiomatic framework. We prove under certain general, model-independent assumptions that such an expansion necessarily has ... More
Flow equation solution for the weak to strong-coupling crossover in the sine-Gordon modelAug 03 1999Dec 15 1999A continuous sequence of infinitesimal unitary transformations, combined with an operator product expansion for vertex operators, is used to diagonalize the quantum sine-Gordon model for 2 pi < beta^2 < infinity. The leading order of this approximation ... More
Kinematic Effects in Radiative Quarkonia DecaysOct 19 2000Non-relativistic QCD (NRQCD) predicts colour octet contributions to be significant not only in many production processes of heavy quarkonia but also in their radiative decays. We investigate the photon energy distributions in these processes in the endpoint ... More
Page's Sequential Procedure for Change-Point Detection in Time Series RegressionAug 06 2013In a variety of different settings cumulative sum (CUSUM) procedures have been applied for the sequential detection of structural breaks in the parameters of stochastic models. Yet their performance depends strongly on the time of change and is best under ... More
Lower bounds on the absorption probability of beam splittersAug 25 2005We derive a lower limit to the amount of absorptive loss present in passive linear optical devices such as a beam splitter. We choose a particularly simple beam splitter geometry, a single planar slab surrounded by vacuum, which already reveals the important ... More
Minima hopping: Searching for the global minimum of the potential energy surface of complex molecular systems without invoking thermodynamicsFeb 04 2004A method is presented that can find the global minimum of very complex condensed matter systems. It is based on the simple principle of exploring the configurational space as fast as possible and of avoiding revisiting known parts of this space. Even ... More
Optimization and Parallelization of a force field for silicon using OpenMPJan 25 2002The force field by Lenosky and coworkers is the latest force field for silicon which is one of the most studied materials. It has turned out to be highly accurate in a large range of test cases. The optimization and parallelization of this force field ... More
Topological Expansion and Exponential Asymptotics in 1D Quantum MechanicsMar 30 1999Borel summable semiclassical expansions in 1D quantum mechanics are considered. These are the Borel summable expansions of fundamental solutions and of quantities constructed with their help. An expansion, called topological,is constructed for the corresponding ... More
Asymptotic Estimates for Some Number Theoretic Power SeriesMay 13 2009We derive asymptotic bounds for the ordinary generating functions of several classical arithmetic functions, including the Moebius, Liouville, and von Mangoldt functions. The estimates result from the Korobov-Vinogradov zero-free region for the Riemann ... More
Tests of Quantum Chromo Dynamics at e^+e^- CollidersMar 06 2006May 23 2006The current status of tests of the theory of strong interactions, Quantum Chromo Dynamics (QCD), with data from hadron production in e^+e^- annihilation experiments is reviewed. The LEP experiments ALEPH, DELPHI, L3 and OPAL have published many analyses ... More
A short proof of Gromov's filling inequalityMar 29 2007We give a very short and rather elementary proof of Gromov's filling volume inequality for n-dimensional Lipschitz cycles (with integer and Z_2-coefficients) in $L^\infty$-spaces. This inequality is used in the proof of Gromov's systolic inequality for ... More
Non critical super strings on world sheets of constant curvatureOct 30 1992Nov 03 1992We consider correlation functions in Neveu--Schwarz string theory coupled to two dimensional gravity. The action for the 2D gravity consists of the string induced Liouville action and the Jackiw--Teitelboim action describing pure 2D gravity. Then gravitational ... More
Lattice QCD with a chiral twistFeb 05 2007In these lectures I explain how chiral symmetry of continuum QCD naturally leads to a class of lattice regularisations known as twisted mass QCD (tmQCD). As compared to standard Wilson quarks, its advantages are the absence of unphysical zero modes, the ... More
One-loop renormalization of the QCD Schrödinger functionalApr 08 1995In a previous publication, we have constructed the Schr\"odinger functional in Wilson's lattice QCD. It was found that the naive continuum limit leads to a well-defined classical continuum theory. Starting from the latter, a formal continuum definition ... More
SQL Queries for Declarative Process Mining on Event Logs of Relational DatabasesDec 01 2015Dec 03 2015Flexible business processes can often be modelled more easily using a declarative rather than a procedural modelling approach. Process mining aims at automating the discovery of business process models. Existing declarative process mining approaches either ... More
Garbage Collection in JyNI - How to bridge Mark/Sweep and Reference Counting GCJul 01 2016Jython is a Java-based Python implementation and the most seamless way to integrate Python and Java. It achieves high efficiency by compiling Python code to Java bytecode and thus letting Java's JIT optimize it - an approach that enables Python code to ... More
Spying on photons with photons: quantum interference and informationJun 15 2016The quest to have both which-path knowledge and interference fringes in a double-slit experiment dates back to the inception of quantum mechanics (QM) and to the famous Einstein-Bohr debates. In this paper we propose and discuss an experiment able to ... More
Separable linear orders and universalityJun 01 2016In various places in the literature it is stated that every separable linear order embeds into the real line. This is, however, not the case, at least not with respect to the usual definition of separability. We correct this misconception.
Convergence of the gradient method for ill-posed problemsJun 01 2016We study the convergence of the gradient descent method for solving ill-posed problems where the solution is characterized as a global minimum of a differentiable functional in a Hilbert space. The classical least-squares functional for nonlinear operator ... More
Novikov homology and noncommutative Alexander polynomialsJun 11 2016In the early 2000's Cochran and Harvey introduced non-commutative Alexander polynomials for 3-manifolds. Their degrees give strong lower bounds on the Thurston norm. In this paper we make the case that the vanishing of a certain Novikov-Sikorav homology ... More
Exponential Orthogonality Catastrophe at the Anderson Metal-Insulator TransitionJun 07 2016We consider the orthogonality catastrophe at the Anderson Metal-Insulator transition (AMIT). The typical overlap $F$ between the ground state of a Fermi liquid and the one of the same system with an added potential impurity is found to decay at the AMIT ... More
An example of quantum imaging: rendering an object undetectableApr 26 2016In this paper we propose and analyse a Gedankenexperiment involving three non-linear crystals and two objects inserted in the idler beams. We show that, besides the behaviour that can be extrapolated from previous experiments involving two crystals and ... More
Deformations of Galois representations and exceptional monodromy, II: raising the levelApr 20 2016Apr 21 2016Building on lifting results of Ramakrishna, Khare and Ramakrishna proved a purely Galois-theoretic level-raising theorem for two-dimensional odd representations of the Galois group of Q. In this paper, we generalize these techniques from type A1 to general ... More
Parameterized Compilation Lower Bounds for Restricted CNF-formulasApr 22 2016We show unconditional parameterized lower bounds in the area of knowledge compilation, more specifically on the size of circuits in decomposable negation normal form (DNNF) that encode CNF-formulas restricted by several graph width measures. In particular, ... More
Decomposable theta divisors and generic vanishingFeb 19 2016Jun 20 2016We study ample divisors X with only rational singularities on abelian varieties that decompose into a sum of two lower dimensional subvarieties, X=V+W. For instance, we prove an optimal lower bound on the degree of the corresponding addition map, and ... More
Starburst galaxies as seen by gamma-ray telescopesJan 24 2016Starburst galaxies have a highly increased star-formation rate compared to regular galaxies and inject huge amounts of kinetic power into the interstellar medium via supersonic stellar winds, and supernova explosions. Supernova remnants, which are considered ... More
Lower Bounds on the mim-width of Some Perfect Graph ClassesAug 04 2016mim-width is a recent graph width measure that has seen applications in graph algorithms and problems related to propositional satisfiability. In this paper, we show linear lower bounds for the mim-width of strongly chordal split graphs, co-comparability ... More
Yet Another Paper about Partial Verb Phrase Fronting in GermanMay 02 1996I describe a very simple HPSG analysis for partial verb phrase fronting. I will argue that the presented account is more adequate than others made during the past years because it allows the description of constituents in fronted positions with their ... More
Cyclotomic Aperiodic Substitution TilingsJun 22 2016Sep 27 2016The class of Cyclotomic Aperiodic Substitution Tilings (CAST) is introduced. Its vertices are supported on the 2n-th cyclotomic field. It covers a wide range of known aperiodic substitution tilings of the plane with finite rotations. Substitution matrices ... More
Fate of QCD sum rules or fate of vector meson dominance in a nuclear mediumApr 06 2006A current-current correlator with the quantum numbers of the omega meson is studied in a nuclear medium. Using weighted finite energy sum rules and dispersion relations for the current-nucleon forward scattering amplitude it is shown that strict vector ... More
Factorization and Non-Factorization of In-Medium Four-Quark CondensatesFeb 07 2005It is well-established for the vacuum case that in the limit of a large number of colors N_c the four-quark condensates factorize into products of the two-quark condensate. It is shown that in the combined large-N_c and linear-density approximation four-quark ... More
Selfconsistent approximations, symmetries and choice of representationOct 26 2006In thermal field theory selfconsistent (Phi-derivable) approximations are used to improve (resum) propagators at the level of two-particle irreducible diagrams. At the same time vertices are treated at the bare level. Therefore such approximations typically ... More
There is no local chiral perturbation theory at finite temperatureJul 17 2004For a low-temperature expansion in QCD it is well-known that the Lagrangian of vacuum chiral perturbation theory can be applied. This is due to the fact that the thermal effects of the heavy modes are Boltzmann suppressed. The present work is concerned ... More
Test particle description of transport processes for states with a continuous mass spectrumNov 23 1999Aiming at a description of transport processes where the dynamically generated width of the states is potentially large a transport equation beyond the quasiparticle approximation is derived in first order gradient expansion. An effective particle number ... More
The Yang-Mills vacuum wave functional thirty-five years laterMar 04 2015The first paper attempting direct calculation of the Yang-Mills vacuum wave functional was published by Greensite in 1979. I review some recent results of the determination of the vacuum wave functional in Monte Carlo simulations of SU(2) lattice gauge ... More